This study describes the development and testing of a virtual reality locomotion system that uses the user’s arm swings as input. This system has also been integrated with audio and haptic feedback that reacts to the user’s velocity and the surface they’re currently walking on, in an attempt to provide an intuitive and immersive VR locomotion experience. To achieve this, an open source ArmSwinger implementation has been adapted, and custom haptic belts were crafted to display haptic feedback around the user’s feet. Tests with three participants have shown that the system is able to be operated even by users unfamiliar with VR, and the addition of locomotion feedback mostly succeeds in improving the user experience, albeit some issues with synchronization were brought up. / Denna studie beskriver utvecklingen och testningen av ett virtuell verklighet lokomotivsystem som använder användarens armsvängningar som ingång. Detta system har också integrerats med ljud och haptisk feedback som reagerar på användarens hastighet och ytan de för närvarande går på, i ett försök att ge en intuitiv och uppslukande VV rörelseupplevelse. För att uppnå detta har en öppen källkod ArmSwinger implementering anpassats och anpassade haptiska bälten har utformats för att visa haptisk feedback runt användarens fötter. Test med tre deltagare har visat att systemet kan drivas även av användare som inte känner till VV, och tillägget av rörelseåterkoppling lyckas främst förbättra användarupplevelsen, även om vissa problem med synkronisering togs upp.

Through the Cenozoic, paleoclimate records show general trends of global cooling and increased aridity, and environments in North America shifted from predominantly forests to more open habitats. Paleobotanical records indicate grasses were present on the continent in the Eocene; however, paleosol and phytolith studies indicate that open habitats did not arise until the late Eocene or even later in the Oligocene. Studies of large mammalian herbivores have documented changes in ecomorphology and community structure through time, revealing that shifts in mammalian morphology occurred millions of years after the environmental changes thought to have triggered them. Smaller mammals, like rodents and lagomorphs, should more closely track climate and habitat changes due to their shorter generation times and smaller ranges, but these animals have received much less study. To examine changes in smaller mammals through time, we have assembled and analyzed an ecomorphological database of all North American rodent and lagomorph species. Analyses of these data found that rodent and lagomorph community structure changed dramatically through the Cenozoic, and shifts in diversity and ecology correspond closely with the timing of habitat changes. Cenozoic rodent and lagomorph species diversity is strongly biased by sampling of localities, but sampling-corrected diversity reveals diversity dynamics that, after an initial density-dependent diversification in the Eocene, track habitat changes and the appearance of new ecological adaptations. As habitats became more open and arid through time, rodent and lagomorph crown heights increased while burrowing, jumping, and cursorial adaptations became more prevalent. Through time, open-habitat specialists were added during periods of diversification, while closed-habitat taxa were disproportionately lost in subsequent diversity declines. While shifts among rodents and lagomorphs parallel changes in ungulate communities, they started millions of years earlier than in larger mammals. This is likely a consequence of the smaller mammal' greater sensitivity to environmental changes and more rapid evolution. These results highlight the importance of examining understudied members of vertebrate faunas for understanding the evolution of terrestrial communities through time.

One of the goals of neuroscience is to classify all of the neurons in the brain. Neuronal types can be defined using a combination of morphology, electrophysiology, and gene expression profiles. Gene expression profiles allow differentiation between cells that share similar characteristics. Leveraging the advantage of Berghia stephanieae (Gastropoda; Nudibranchia), which has around 28,000 neurons, I constructed high-throughput single-neuron transcriptomes for its whole brain. I produced a single-cell dissociation protocol and a custom data analysis pipeline for data of this nature. Around 129,000 cells were collected from 18 rhinophore ganglia and 20 circumesophageal ring ganglia (brain), consisting of the cerebropleural, pedal, and buccal ganglia. Messenger RNA libraries were constructed using the 10X Genomics’ Chromium platform. After library preparation, around 1,000 cells were recovered and sequenced. The HTStream package was utilized to trim off unwanted sequences from the raw reads and remove PCR duplicates and other contamination, then the salmon alevin package was employed to construct gene-by-cell matrices containing all the transcripts for each gene in each cell. The Seurat pipeline was used to extract this expression data from the matrices, normalize it, and perform dimensionality reduction. The cells were clustered based on similarities in their gene expression profiles. The cells formed eight clusters on a UMAP graph, each having distinct marker genes. Additionally, one cluster was composed of almost exclusively cells from the rhinophore ganglia, accounting for 30% of all rhinophore ganglion cells in the sample. Cells from the rhinophore ganglia are as heteregenous as cells from the rest of the brain, with cells forming six clusters. Cell populations that express the same neurotransmitter were identified for a wide range of both small-molecule neurotransmitters and neuropeptides. In a separate project, the locomotion of Berghia was recorded over 9 days with 2 lighting regimes: LD first and DD first. The results suggest that locomotion of Berghia is governed by circadian clock and that Berghia is nocturnal. Hunger state likely plays a role in modulating this circadian rhythm.

京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第18483号 / 生博第312号 / 新制||生||41(附属図書館) / 31361 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 上村 匡, 教授 垣塚 彰, 教授 藤田 尚志 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

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